Some webmasters prefer a pure Flash site, as it can look very impressive. While Google can index Flash content to a certain extent, it is very unlikely that the Flash page will receive a good ranking in Google.
What's the problem with Flash pages?
Flash content can not be indexed by search engines. If the site is a pure Flash site, then you can be sure that the search engines will not be able to see 95% of the contents of your website.
Google has made several official statements regarding Flash content:
"Search engines are text based. This means that for a website to be scanned and indexed, your content must be in text format. All content contained in these files should be available in text format or won't be accessible to search engines.
We recommend using the rich-media technologies like Flash mainly for decorative purposes, and instead using the HTML for content and navigation.
Make sure your website is reasonable, seamless experience for visitors without Flash. This may involve the creation of a single HTML equivalent of Flash content, which is automatically displayed to the viewers that can not view Flash."
Adding your website content in the noScript tag won't help!
Theoretically, adding your website content in the noscript tag on your webpages ensures that the search engines are able to get the right content. Unfortunately, Google's John Mueller suggests that this does not work anymore:
"One of the problems with noScript is that it's a bit of an abuse by spammers, so search engines can handle it with a little suspicion.
So if this is really important content, then I would not count on all the search engines treat your noScript elements in the same way as normal, visible, static content on your webpages. If it is just for the comments, so it might be worth considering."
What does this mean for your website?
If you need a reasonable amount of visitors from search engines like Google, do not use Flash or other multimedia elements for the main content of your webpages:
Use the free search engine spider simulators to see how search engines see your website. If the spider simulator does not display the contents of your website, it might be time to revisit and redesign your site.